Welcome to the forum!
A little helpful information:
You don't have any of the brake activated LSD that they discuss, those didn't become available till later years.
Difference between lockers and open diffs:
The best (cheapest) thing you can do to help your current situation is to air down your tires when you are off-road. Dropping your air pressure down to ~15-20 psi will effectively double your contact patch and greatly improve traction. No - it won't make much difference when you've got 1 front wheel and 1 rear wheel that have lost traction and thereby spinning uselessly, but it will make a big difference in keeping you out of those sorts of situations, i.e. sliding into the ruts.
Airing your tires back up will require a quality air pump. Anything the plugs into the cigarette lighter is garbage and you can expect it to fail. Here's a link to a review of the cheapest "worthy" air pump I'm aware of:
air compressor test
The MF-1050 (aka MV50) is sold at a bunch of different auto parts stores. I haven't seen it for sale as cheap as he says in that review (that was 2005), but I did just pick one up at O'Reilly for ~$80.
You can upgrade your existing axles to limited slip or lockers and there are several different ways to do it - none of them cheap! Learn to drive what you have effectively and then make the decision whether you want/need to upgrade. Learning to understand the shortcomings of open diffs can help keep you from putting yourself into problem situations in the first place.
HTH
David